Measuring oxygen content of air-failed

[fuzuqoma]

Hello. for my 7th grade science fair I performed the steel wool in the inverted test tube experiment. I used fine stool wool from hardware store, six test tubes (3 with steel wool, 3 without), instead of individual beakers I inverted all six (attached to peg board), over a tub of water....after six days....nothing. What could be wrong? Halfway through the experiment, I did take one test tube and briefly fill it with water and reinverted...thinking maybe the wetting steel wool would accelerate oxygen use...and if you look real hard, the water may have risen a tiny amount in this tube? I don't know...help

[alyssaSTEMg]

Hi!

There are several things that may have gone wrong in the experiment. Your wool may not have had excess iron in it, or your test tubes may not have been submerged enough in the water. But you said that the one test tube that you soaked in water had a small result? I think the problem may have been step 6 from the experiment link:

https://www.sciencebuddies.org/science- ... #procedure

Make sure you are soaking all three of the test tubes with wool inside, and I think you will get better results.

Thankyou!